Sofas and uncaused events

Consider three worlds where a sofa rises and in each of which Alice and Bob have the same lifting powers, and nothing beyond Alice and Bob influences the sofa’s rise.

• w₁: the sofa is lifted by Alice and Bob, with neither of them sufficiently power to lift the sofa on their own

• w₂: the sofa rises without Alice or Bob exerting their lifting abilities

• w₃: the sofa rises with Alice exerting her lifting abilities.

If we think w₁ and w₂ are both possible, we should think that w₃ is also possible. It would be too weird if eliminating both Alice and Bob’s exertions were compatible with the sofa rising, but somehow keeping Alice’s exertions precluded the sofa from rising.

But in w₃, Alice can’t be the cause of the sofa’s rising. But she seems to have the same influence on it as in w₁. So it seems she is a merely partial cause of the sofa’s rising.

However, Alice can’t be a merely partial cause of the sofa’s rising without being a part of a full cause of the sofa rising. But nothing else influences the sofa’s rise. So, there is no full cause, and yet Alice can’t be a merely partial cause.

Thus, w₃ is impossible. But if w₁ and w₂ are possible, so is w₃. So, w₂ is impossible. So, uncaused events are impossible.

Two kinds of partial causation

It’s interesting that there are at least two significantly different kinds of partial causation. In both of the following cases it seems reasonable to say that x partially causes y:

1. x and z together cause y

2. x causes z and z is a part of y.

I.e., the partiality can be on either side of the causal relation. And one might even combine the two, no?

My previous post was about partial causation where the partiality was on the side of the cause, not the side of the effect.

Partial causation and causeless events

1. If ordinary events can happen without any cause at all, they can happen with a partial cause and no full cause.

2. A partial cause is a part of a full cause.

3. Nothing can happen with a partial cause and no full cause.

4. So, ordinary events cannot happen causelessly.

The argument for (2) is that (2) is the most obvious way to define a partial cause.

The argument for (1) is as follows. Suppose you and I lift a sofa in world w₁ in such a way that the exertion of each of us only partly explains the rising of the sofa, as neither exertion is enough to cause the rising. If ordinary events can happen without any cause at all, there is a world w₂ where the sofa rises causelessly, with neither you nor I doing anything. But if w₁ and w₂ are possible, likewise a world w₃ is possible where only I exert myself just as in w₁ and you sit back and the sofa rises in response to my exertion, and nothing else causally impacts the sofa’s rising. Since my exertion is not enough to cause the rising of the sofa in w₁, and in w₃ I exert myself to the same degree, my exertion is no more a full cause of the sofa’s rising in w₃ than it is in w₁. Hence, in w₃, I partially causes the sofa to rise, without there being a full cause, just as the consequent of (1) claims.

If I were inclined to deny (4), I would want to argue that (2) is not the right way to define a partial cause. But I don’t know a better way.